Dietary P regulates phosphate transporter expression, phosphatase activity, and effluent P partitioning in trout culture
MetadataShow full item record
Cited times in Scopus
Phosphate utilization by fish is an important issue because of its critical roles in fish growth and aquatic environmental pollution. High dietary phosphorus (P) levels typically decrease the efficiency of P utilization, thereby increasing the amount of P excreted as metabolic waste in effluents emanating from rainbow trout aquaculture. In mammals, vitamin D3 is a known regulator of P utilization but in fish, its regulatory role is unclear. Moreover, the effects of dietary P and vitamin D3 on expression of enzymatic and transport systems potentially involved in phosphate utilization are little known. We therefore monitored production of effluent P, levels of plasma vitamin D3 metabolites, as well as expression of phosphatases and the sodium phosphate cotransporter (NaPi2) in trout fed semipu diets that varied in dietary P and vitamin D3 levels. Mean soluble P concentrations varied markedly with dietary P but not with vitamin D3, and constituted 40–70% of total effluent P production by trout. Particulate P concentrations accounted for 25–50% of effluent P production, but did not vary with dietary P or vitamin D3. P in settleable wastes accounted for <10% of effluent P. The stronger effect of dietary P on effluent P levels is paralleled by its striking effects on phosphatases and NaPi2. The mRNA abundance of the intestinal and renal sodium phosphate transporters increased in fish fed low dietary P; vitamin D3 had no effect. Low-P diets reduced plasma phosphate concentrations. Intracellular phytase activity increased but brushborder alkaline phosphatase activity decreased in the intestine, pyloric caeca, and gills of trout fed diets containing low dietary P. Vitamin D3 had no effect on enzyme activities. Moreover, plasma concentrations of 25-hydroxyvitamin D3 and of 1,25-dihydroxyvitamin D3 were unaffected by dietary P and vitamin D3 levels. The major regulator of P metabolism, and ultimately of levels of P in the effluent from trout culture, is dietary P.
CitationColoso, R. M., King, K., Fletcher, J. W., Weis, P., Werner, A., & Ferraris, R. P. (2003). Dietary P regulates phosphate transporter expression, phosphatase activity, and effluent P partitioning in trout culture.
This project was supported by the Northeastern Regional Aquaculture Center (NRAC)-USDA Grant no. 94-38500-0044) and USDA-CSREES-NRI Grant no. 2001-35102-09881. R. Ferraris’ laboratory also received support from NSF-IBN9985805. We thank S. Basantes, A. Garcia, J. Choi, and F. Liu for help in the chemical analyses of the water, fecal, and carcass samples, Dr. M. Subramanyam for his suggestions on the formulation of the semi-purified diets, P. Farrell for the expert technical assistance during field sampling, F. Jarder for the proximate analyses of the diets, K. Powers of Pequest Fish Hatchery for the fish and Dr. A. Ritter for statistical advice.
- Journal Articles 
Showing items related by title, author, creator and subject.
Growth response of cultured larvae of silver therapon Leiopotherapon plumbeus (Kner, 1864) in outdoor tanks in relation to fertilizer type and fish density This study evaluated the effects of fertilizer type and fish density on early growth and survival of silver therapon Leiopotherapon plumbeus (Kner, 1864) larvae reared in outdoor tanks. In the first experiment, larvae (1.92 ± 0.09 mm total length) were stocked into nine, 4 m3 tanks at an initial density of 0.5 larvae L-1 and reared for 42 days at an ambient temperature of 28.8–30.7°C. Three treatments with three replicates each were compared: organic (chicken manure, OF) or inorganic fertilizers (ammonium phosphate, IF) applied once every 2 weeks, and the unfertilized (NF) tanks serving as the control group. Water quality, zooplankton densities, survival or growth of L. plumbeus larvae did not vary significantly in either fertilized or unfertilized tanks. Fertilization resulted in elevated nutrient concentrations, which did affect survival (2.10%–6.07%) of the fish larvae. In the second experiment, larvae were stocked at densities of 0.4 or 0.6 larvae L-1 in tanks fertilized at 4–5 days interval with OF and IF for 30 days. Growth performance of L. plumbeus larvae was affected by fish density, with significantly larger (20.04 ± 2.65 mm in total length) and higher specific growth rate (SGR; 6.97 ± 0.48% day-1) at 0.4 larvae L-1 than at 0.6 L-1. Fry production did not vary significantly between fish density treatment groups given the same fertilizer types, but survival rates were improved at 0.4 L-1. Together, production of L. plumbeus larvae in outdoor tanks can be optimized at a lower stocking density, regardless of the type of fertilizer used.
Oxygen, sulphide and nutrient uptake of the mangrove mud clam Anodontia edentula (Family: Lucinidae) MJHL Lebata -
Marine Pollution Bulletin, 2001 - ElsevierOxygen, sulphide and nutrient (ammonia, nitrite and phosphate) uptake of Anodontia edentula was measured. Oxygen and sulphide were measured from sealed containers provided with 1 l fresh mangrove mud (sulphide source) and seawater (oxygen source) with two treatments (with and without clam) at 16 replicates each. Oxygen, sulphide and other parameters were measured at days 1 (initial), 3 and 5 (final). Nutrients were measured from containers filled with 1.5 l wastewater from a milkfish broodstock tank with two treatments (with and without clam) at eight replicates each. Ammonia, NO2 and PO4 were measured at days 0 (initial) 3, 6, 9 and 12 (final). Results showed significantly decreasing oxygen and sulphide concentrations in treatment with clams (ANOVA, p < 0.001). A significantly higher ammonia concentration (ANOVA, p < 0.05) was observed in treatment with clams while no significant difference was observed in nitrite and phosphate between the two treatments. A decreasing ammonia and an increasing nitrite trend was also observed in both treatments starting at day 3.